The Effect of Architectural Configurations on the Biological Light Response in Residential Buildings

Abstract

Daylight has beneficial psychological and health effects that range from enhanced alertness, mood improvements, increased productivity, and well-being. Recently, the interest in non-visual (also called biological) effect of light has increased substantially. Yet, a limited number of research has investigated the non-visual effects of light in Nordic climates.
The aim of this thesis is to assess the effect of changing the building configuration on the average Biological Light Response (BLR) that would also translate to a proxy for alertness. This research implements a simulation methodology to simulate the BLR on a residential building located in Malmö Sweden. The building was parametrically modelled using Grasshopper plugin in Rhino, while Honeybee, Ladybug, and Lark plugins for Grasshopper were used to develop the BLR simulation workflow.
In the BLR simulation method, four days (two equinoxes and solstices) were simulated with their respective sky conditions for an east- and a west-facing apartment. The simulation considered three CIE sky conditions (overcast, intermediate, and clear) with their corresponding Correlated Colour Temperature (CCT).
The results of the simulation in circadian illuminance were compared to minimum and maximum thresholds, indicating the required illuminance to reach 0% and 100% BLR respectively. The BLR percentage was then calculated indicating the average alertness level reached in the space.
The simulation results of the base case showed that only March and June days reached an average BLR near the set threshold (75% in this case based on previous research). The total average of the four days was approximately 50%. To improve the BLR of current building design, several parameters in the building were varied, and the best configurations were the ones without the balcony and sunspace, as these elements obstruct glazing areas.
In conclusion, the BLR simulation workflow enabled a sound evaluation of the non-visual effects of daylight, paving the way for architects to consider the wellbeing aspect related to daylight during the early design stages.

Popular Abstract

Daylighting in buildings is a broad research topic that links architectural design with building engineering, and considers human physiology and behavior. Past research focused on the visual effects of light while more recent research addresses non-visual effects of light. This recent research is interested in how light affects the human health, specifically the circadian rhythm that controls many hormones and functions in the human body on a daily basis. Considering this topic in residential buildings is a crucial aspect as humans are subject to their first and last light exposure at their homes, which would have an important impact on the daily circadian rhythm. Evaluating this in a residential building is however a very complex process as many variables contribute such as wavelength or spectrum distribution, time of exposure, and history of light. The method used in this thesis considers the daylight spectrum, and time of exposure as a simple method that would be indicative of the space performance in terms of the biological light response.
To evaluate the considered building, four days (two equinoxes and solstices) were simulated with their respective sky conditions for an east and a west-facing apartment. The sky conditions were calculated from the weather file data using a ‘sky clearance index’ equation. Four critical points were analyzed that represent the most common seating and standing positions in the two apartments. Each point was analyzed by simulating the vertical illuminance reaching the eye in four orientations (north, south, east and west).
The Grasshopper plugin, ‘Lark’ was used in this thesis, in addition to Honeybee and Ladybug to perform these simulations. The two main reasons for using Lark is first to add color information to standard CIE sky files by representing each sky condition (overcast, intermediate, and clear) by a corresponding Correlated Color temperature (6500, 8500, 25000 respectively). The second reason is to be able to convert the ‘photopic illuminance’ that is used in all simulation software to ‘circadian illuminance’ as the human sensitivity to the non-visual response of light is shifted towards blue wavelengths in comparison to the photopic sensitivity curve.
Several calculations were carried out to determine the minimum and maximum required ‘circadian illuminance’ values and the corresponding percentage of non-visual effect or alertness. A threshold of 75% was arbitrarily selected based on previous research and was considered the minimum average of the whole space. The results showed that the base case and most of the other cases did not reach this average threshold of 75% when averaging the four days, but it was reached when taking the average of March and June. The average threshold was not reached in December at all even with a fully glazed apartment, primarily because of the sun position in December in relation to the east and west apartments.
After several simulations, the best simulated case was a north and a west-oriented window without balcony and sunspace, and with a double glazed window. The major improvement in the average non-visual effect was after removing the balcony, accordingly maximizing unobstructed glass areas is therefore a recommendation in Swedish climatic conditions.

• author: Shalaby, Maha
• supervisor: Marie-Claude Dubois
• organization: Division of Energy and Building Design
• course: AEBM01 20161
• year: 2017
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Circadian light, non-visual effects, alertness, design configurations
• language: English
• id: 8905319
• date added to LUP: 2017-05-15 13:52:51
• date last changed: 2017-05-15 13:52:51